After struggling with 40 minutes of exposures and various UV lamps a lot of overexposed and underexposed materials, only possible decision was to make a new and better UV lamp.
Considering I was lucky that our famous photographer Josip Klarica gave me a 50x70cm contact frame this determined the size of my new UV lightbox.
UV LED strip lamps and a 12V-20A DC converter arrived from China. I took fans from old computers and wooden parts were purchased in Bauhaus store.
Finally, some screws, varnish, and glue. Pieces were cut, sanded and double-painted with oil paint. After proper drying everything was put together.
The holder plate for UV LEDs was the second part of the project.
The UV LED reel is cut into 21 strips with 39 diodes each. Since the tapes are self-adhesive they just have to be pressed carefully on the carrier. The edges are soldered to the “+” or “-” joint wire which is 4 mm thick and leading to the DC converter.
The wires are slightly over-sized, but this avoids overheating.
The diode panel is 2 cm away from the ceiling of the box so that air can flow around it while the diodes are working.
As it turned out, at 6 minute exposure the heating was so low that it could work without a fan.
The first trial showed that the effort was justified.
The contact copy frames are 7.5cm away from the diodes, the light is even, and the exposures are from 6 min (cyanotype) to 2 min (gumoil), and now I have full control over exposure.
— THE FIRST STEP DONE —
SEVERAL STAGES OF UV BOX CONSTRUCTION
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